(1) The hours of work in relation to adult motor transport workers on each day shall be so fixed that no period of work shall exceed five hours and that no such motor transport worker shall work for more than five hours before he has had an interval for rest for at least half-an-hour:
     Provided that the provisions of this sub-section in so far as they relate to interval for rest shall not apply to a motor transport worker who is not required to work for more than six hours on that day.
     (2) The hours of work on each day shall be so fixed that a motor transport worker is, except in any case referred to in the second proviso to section 13, allowed a period of rest of at least nine consecutive hours between the termination of duty on any one day and the commencement of duty on the next following day.